What may be one of the oldest known rocks from Earth has been found in the material that Apollo 14 astronauts brought home from the moon nearly 50 years ago.

It is thought that the rock, made up of quartz, feldspar and zircon, crystallised deep beneath Earth’s surface about 4bn years ago and was catapulted towards the moon in a collision with an asteroid or comet soon afterwards.

“It is an extraordinary find that helps paint a better picture of early Earth and the bombardment that modified our planet during the dawn of life,” said David Kring, a senior staff scientist at the Lunar and Planetary Institute in Houston, Texas.

Chemical analysis of the 2g fragment suggests it formed more than 12 miles underground in an oxidising environment, which can be found on Earth but not on the moon. A major impact then excavated the rock and blasted it into space, according to a report in Earth and Planetary Science Letters.

At the time of the collision, the moon was three times closer to Earth than it is today. After the rock came to rest on the lunar surface, another impact 3.9bn years ago partially melted and buried it, scientists believe.

The final impact that affected the rock happened about 26m years ago when an asteroid slammed into the moon and made the Cone crater, measuring 340 metres wide and 75 metres deep, near the Apollo 14 landing site.

That impact resurfaced the rock, which was then collected by the Nasa astronauts. The Apollo 14 crew spent more than 33 hours on the lunar surface in February 1971 and brought home nearly 43kg of moon rocks.

The researchers, led by Jeremy Bellucci and Alexander Nemchin at the Swedish Museum of Natural History and Curtin University in Australia respectively, concede that the rock may have formed on the moon, but argue that this would have required conditions not previously seen in lunar samples.

To have a lunar origin, the rock would have had to crystallise at tremendous depth where rocks tend to have very different compositions, they write.

The Earth formed in the early solar system 4.5bn years ago. The oldest known fragment of Earth rock is a zircon crystal from Western Australia. The sliver of material, the same width as two human hairs, has been dated to 4.4bn years old.